I don't remember those parts, so I'm going to say the motor. The regulator is just a big metal scissors that lifts the window. The motor mounts to the regulator, so you'll swap it out to the new unit.
The plastic guides that slide within the tracks of the regulator (the one that broke on mine could not be serviced) are usually what break. Make sure you really grease up the tracks before putting the panel back on.
EDIT -
Here is a picture of it. You can see one of the white plastic guides at the 8:00 position. That is what broke on mine. If the other ones are broken, I think they can be replaced. If you replace the regulator, and it doesn't come with those guides, order new ones.
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